SIMS: Smart Inventory Management System

1. SIMS:Smart Inventory Management System Group 37 Masaki Negishi & Anthony Fai ECE 445 Senior Design April 27, 2005

2. Introduction • SIMS provides a cost effective solution for the management of inventory which leverages RFID technology. • Combines an antenna array to a single RFID reader to map out an area for inventory detection

3. Features • PC serial interface • Compatible with RFID Readers and Antennas • Up to 8 outputs per unit • Expandable, modular design

4. The images in this presentation have been reduced to screen quality (saves space) Format Picture -> Compress The SIMS System

5. System Overview • Hardware: • Power Supply, PC Interface Processing Unit, RF Switching Unit • TI HF RFID Reader, TI HF RFID Antenna, TI HF RFID Transponders • Software: • PC control for antenna switching

6. System Overview

7. Hardware Overview (In House Manufactured) • Power Supply • Takes 6Vdc from AC/DC wall converter and converts to stable 5Vdc • PC Interface Processing Unit • PC communication with system • RF Switching Unit • Switching of RF signal from reader to selected antenna

8. PC Interface Processing Unit • PIC Microprocessor • RS232 Serial Communication with PC • Sends output to RF Switching Unit

9. Black will have better contrast on a projector PC Interface Processing Unit (Schematic)

10. RF Switching Unit • Takes in input from RFID reader • Four outputs per board (expandable) • Relay switching

11. RF Switching Unit (Schematic)

12. PIN Diode Switching Unit (Eliminated) • Employ PIN Diodes for Switching • Great performance for small peak to peak AC signal (low power) • Poor performance for large peak to peak AC signal (high power) • Introduce impedance mismatch

13. Power Supply (Main Idea) • Supplies +5 Vdc and GND to switch and control units • Maximum current: 1A • More stable compared to 5V from the wall

14. Black will have better contrast on a projector Power Supply (Schematic)

15. We always like to see measured data (especially with waveforms)! Power Supply (Results) • Vmax: 5.023 V • Vmin: 4.975 V • Max. Ripple: 48.44mV • Freqnency: 95.057KHz

16. Hardware Overview (Outsourced) • TI RFID S6500 HF Reader • TI RFID HF Transponders • TI RFID HF 13.56 MHz Antenna (RI-ANT-T01A)

17. TI RFID S6500 HF Reader • RFID Reader • Necessary to read and write to transponders • Can be connected to PC through RS232 • Operating Frequency of 13.56 MHz (HF) • Output voltage of 48 V peak-to-peak • Power output of 4 W

18. TI RFID HF Transponders • Transponders • Receives 13.56MHz of the signal from the reader, and sends back a signal to the reader • Consists of a loop antenna and a chip microprocessor

19. Factors Influencing Communication with Tags • Orientation of tag with respect to antenna • Environment around tag (e.g. metals, liquids) • Background Noise

20. Recommendations for Tag Placements • Parallel to antenna • Away from metals • Within reading range of antenna (~25 cm)

21. TI RFID HF 13.56 MHz Antenna • Used to transmit and receive signals. • Used for Magnetic • Tuned at 13.56 MHz • Input Impedance of 50 Ohms

22. Loop Antenna (In House) • Followed Texas Instruments’ Antenna Cookbook • 50cm x 50cm • Made of copper tape and wooden board • T-matching network • Reading range of 1 mm (SWR ~ 2.2)

23. Black will have better contrast on a projector Loop Antenna (Self-Made) • Measurement Results (SWR = 60.832)

24. Loop Antenna (RI-ANT-T01A) • Dimension: 337mm x 322mm x 38mm • Matched to 50 Ohms • Maximum Reading Range: 50cm

25. Black will have better contrast on a projector Loop Antenna (RI-ANT-T01A) • Measurement Results 1: Vertical, Away from Metal • SWR = 1.004

26. Black will have better contrast on a projector Loop Antenna (RI-ANT-T01A) • Measurement Results 2: Horizontal, Sitting on Lab Table • SWR = 1.636

27. Black will have better contrast on a projector Loop Antenna (RI-ANT-T01A) • Measurement Results 3: Close to Lab Equipments • SWR = 5.111

28. Black will have better contrast on a projector Overall Z-Parameters • SIMS System + Antenna Results During Operation • SWR = 1.349

29. Factors Influencing Antenna Impedance • Orientation • Environment (e.g. metals, liquids) • Noise • Antenna is operating always in near field since wavelength is 22 meters!

30. Just about the maximum amount of text on a slide Antenna Recommendations • Antennae must be placed first, then tuned. • May need multiple antennae at one station for more complete coverage (and avoid nulls from environmental factors) • Larger antennae for longer reading range • Do notcompletely trust antenna cookbooks because they are unreliable!  Buy one antenna firstand analyze it.

31. Software • PERL software • Takes in user input and sends out two HEX digits through RS232 serial port (I/O) • PIC software • Takes in input from RS232 serial port and sends logic high to corresponding pins

32. PERL Software • Serial.pl • Takes in keyboard inputs in HEX • Must read header “AF” followed by two HEX digits (e.g. AF06) • Send out input from COM 2 to PIC • Checks to see if PIC received correct signal

33. PIC Software • Switch0331.hex • Takes input from RS232 and sends logic high to corresponding outputs • Will only respond if header “AF” is seen • Sends back to PC its output

34. Room Setup • Map out room and give coordinates to each antenna • For example, antenna B-2 can correspond to the secretary’s desk

35. Future Hardware Development • Improved Switching Unit for longer lifetime and higher signal isolation • Increased number of antenna outputs • Improved Antenna Design • Larger loop antenna • More stable impedance matching network and BALUN

36. Future Software Development • Friendly user online interface (HTML) • Information processing on transponder data • Network with central server

37. RFID Frequency Comparison

38. SWOT Analysis of SIMS

39. Credits • Mr. Richard Martin Cantzler, II • Professor P. Scott Carney • Mr. Nicholas Soldner • Professor Jennifer T. Bernhard • Professor Steven J. Franke

40. Thank You